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The Return of Air-Breathing Engines

I was reading recently about the Skylon space plane. A pretty cool name, which reminds me of those robotic guys with the light bouncing back and forward where their eyes should be – the vintage Cylons of Battlestar Galactica.

The Skylon spaceplane is a concept for a Single Stage to Orbit (SSTO) plane, which has been a holy grail for the aerospace industry for many decades.

Although the theory of payload Vs rocket mass takes concepts in the direction of multi-staging and non-renewable spacecraft – such as the good old Saturn V and modern equivalent the SpaceX Falcon 9 – the ability to reuse the same spacecraft also makes good economic sense. All rocketry components are damn expensive. Besides it’s such a damn cool idea to be able to get into a spaceplane at the local airport, taxi down the runway and blast into orbit.

What may make this particular SSTO dream feasible is the return of the air-breathing engine. Some of you might remember the HOTOL concept from the 1980s. The moniker stood for Horizontal TakeOff and Landing. I remember being really excited about this joint venture between Rolls Royce and British Aerospace, but apparently funding was cut in 1988 due to serious design flaws and lack of advantage over contemporary launch systems.

Like HOTOL, Skylon features air-breathing engines that use oxygen in the atmosphere as the fuel oxidant [it later switches to liquid oxygen in space]. The majority of fuel tankage is reserved for hydrogen, removing one heck of lot of weight compared to say a shuttle with its big external tank of hydrogen and oxygen. One key feature of the Skylon’s SABRE engines is the cooling of the intake air, which enables a doubling of the efficiency.

The estimated top speed of Skylon is over 30,000 km/h. This gives the craft plenty of scope to fill the niche left by the ill-fated Concorde, with sub-orbital flight times of around 4 hours from London to Sydney. Having suffered through two 30 hour flights to the USA in economy I can’t wait.

The initial goal is to carry payloads to space stations by 2022. English developer Reaction Engines hope to have a working prototype flying by 2016, and a fleet of the craft over the next decade. They are impressive craft. Each will be approximately 82 metres in length with a price tag of around $1.1 billion US.

The spaceplane is a very sleek looking craft. Check out the wikipedia page for graphics.